Correlation between acoustic divergence and phylogenetic distance in soniferous European gobiids (Gobiidae; Gobius lineage)

In fish, species identity can be encoded by sounds, which have been thoroughly investigated in European gobiids (Gobiidae, Gobius lineage). Recent evolutionary studies suggest that deterministic and/or stochastic forces could generate acoustic differences among related animal species, though this has not been investigated in any teleost group to date. In the present comparative study, we analysed the sounds from nine soniferous gobiids and quantitatively assessed their acoustic variability. Our interspecific acoustic study, incorporating for the first time the representative acoustic signals from the majority of soniferous gobiids, suggested that their sounds are truly species-specific (92% of sounds correctly classified into exact species) and each taxon possesses a unique set of spectro-temporal variables. In addition, we reconstructed phylogenetic relationships from a concatenated molecular dataset consisting of multiple molecular markers to track the evolution of acoustic signals in soniferous gobiids. The results of this study indicated that the genus Padogobius is polyphyletic, since P. nigricans was nested within the Ponto-Caspian clade, while the congeneric P. bonelli turned out to be a sister taxon to the remaining investigated soniferous species. Lastly, by extracting the acoustic and genetic distance matrices, sound variability and genetic distance were correlated for the first time to assess whether sound evolution follows a similar phylogenetic pattern. The positive correlation between the sound variability and genetic distance obtained here emphasizes that certain acoustic features from representative sounds could carry the phylogenetic signal in soniferous gobiids. Our study was the first attempt to evaluate the mutual relationship between acoustic variation and genetic divergence in any teleost fish

Apparent Shear Sensitivity of Molecular Rotors in Various Solvents

Fluorescent environment-sensitive dyes often change their spectral properties concomitantly with multiple solvent properties, such as polarity, protonation, hydrogen bond formation, or viscosity. Careful consideration of the response is needed when a fluorescent dye is used to report a single property. Recently, we observed an increase of emission intensity of viscosity-sensitive molecular rotors in fluids subject to flow and speculated that either polar-polar interaction or hydrogen bond formation play a role in the apparent flow sensitivity. In this study, we show experimental evidence that photoisomerization to an isomer with a lower quantum yield, first proposed by Rumble et al. (J Phys Chem A 116(44):10786-10792, 2012), plays a key role in the observed phenomenon. We subjected four molecular rotors with different electron acceptor motifs to fluid flow in solvents of different polarity and ability to form hydrogen bonds. We also measured the isomerization dynamics in a custom fluorophotometer with extremely low light exposure. Our results indicate that the photoisomerization rate depends both on the solvent and on the electron acceptor group, as does the recovery of the original isomer in the dark. In most solvents, recovery of the dark isomer is much more rapid than originally reported, and a state of quasi-equilibrium between both isomers is possible. Moreover, the sensitivity (i.e., relative intensity increase at the same flow rate) is also solvent-dependent. The intensity increase can be detected at very low velocities (as low as 0.06 mm/s). Characteristic for fluorescent dyes is the high spatial resolution, and no flow measurement device with comparable sensitivity and spatial resolution exists, although the nature of the solvent needs to be taken into account for quantitative flow measurement

Understanding mechanobiology in cultured endothelium: A review of the orbital shaker method

A striking feature of atherosclerosis is its highly non-uniform distribution within the arterial tree. This has been attributed to variation in the haemodynamic wall shear stress (WSS) experienced by endothelial cells, but the WSS characteristics that are important and the mechanisms by which they lead to disease remain subjects of intensive investigation despite decades of research. In vivo evidence suggests that multidirectional WSS is highly atherogenic. This possibility is increasingly being studied by culturing endothelial cells in wells that are swirled on an orbital shaker. The method is simple and cost effective, has high throughput and permits chronic exposure, but interpretation of the results can be difficult because the fluid mechanics are complex; hitherto, their description has largely been restricted to the engineering literature. Here we review the findings of such studies, which indicate that putatively atherogenic flow characteristics occur at the centre of the well whilst atheroprotective ones occur towards the edge, and we describe simple mathematical methods for choosing experimental variables that avoid resonance, wave breaking and uncovering of the cells. We additionally summarise a large number of studies showing that endothelium cultured at the centre of the well expresses more pro-inflammatory and fewer homeostatic genes, has higher permeability, proliferation, apoptosis and senescence, and shows more endothelial-to-mesenchymal transition than endothelium at the edge. This simple method, when correctly interpreted, has the potential to greatly increase our understanding of the homeostatic and pathogenic mechanobiology of endothelial cells and may help identify new therapeutic targets in vascular disease

Effect of wood smoke exposure on vascular function and thrombus formation in healthy fire fighters

Background: Myocardial infarction is the leading cause of death in fire fighters and has been linked with exposure to air pollution and fire suppression duties. We therefore investigated the effects of wood smoke exposure on vascular vasomotor and fibrinolytic function, and thrombus formation in healthy fire fighters. Methods: In a double-blind randomized cross-over study, 16 healthy male fire fighters were exposed to wood smoke (~1 mg/m3 particulate matter concentration) or filtered air for one hour during intermittent exercise. Arterial pressure and stiffness were measured before and immediately after exposure, and forearm blood flow was measured during intra-brachial infusion of endothelium-dependent and -independent vasodilators 4–6 hours after exposure. Thrombus formation was assessed using the ex vivo Badimon chamber at 2 hours, and platelet activation was measured using flow cytometry for up to 24 hours after the exposure. Results: Compared to filtered air, exposure to wood smoke increased blood carboxyhaemoglobin concentrations (1.3% versus 0.8%; P &lt; 0.001), but had no effect on arterial pressure, augmentation index or pulse wave velocity (P &gt; 0.05 for all). Whilst there was a dose-dependent increase in forearm blood flow with each vasodilator (P &lt; 0.01 for all), there were no differences in blood flow responses to acetylcholine, sodium nitroprusside or verapamil between exposures (P &gt; 0.05 for all). Following exposure to wood smoke, vasodilatation to bradykinin increased (P = 0.003), but there was no effect on bradykinin-induced tissue-plasminogen activator release, thrombus area or markers of platelet activation (P &gt; 0.05 for all). Conclusions: Wood smoke exposure does not impair vascular vasomotor or fibrinolytic function, or increase thrombus formation in fire fighters. Acute cardiovascular events following fire suppression may be precipitated by exposure to other air pollutants or through other mechanisms, such as strenuous physical exertion and dehydration.Originally included in thesis in manuscript form.</p